Engine starter drive



Aug. 24, 1948. D. L'. MILLER ENGINE STARTER DRIVE Filed May 12. 1945 H vr l iff;

INVENTO-R.' ,Qnaldof WITNESS aanneming. 24, 194s ICE ENGINE STARTERDRIVE Donald L. Miller, Pine City, N. Y.,assignor to Bendix AviationCorporation, South Bend, Ind., a corporation oi' Delaware Application12, 1945, Serial No. 593,398

12 Claims; (m. 'i4-7) The present invention relates to an engine starterdrive and more particularly to that type of starting drive in which apinion is maintained in cranking engagement with -a gear on the engineto be started as long as the starting circuit remains energized.

It is an object of the present invention to provide a novel enginestarter of the above type elnbodying a starting circuit and in which astarter pinion is held in engagement with a gear on the engine to bestarted until the starting circuit is interrupted.

It is a further object to provide such a device, the parts of which aresimple and economical to manufacture, easily accessible for servicingand repair and of durable construction.

It is a further object to provide such a device incorporating means forlatching the pinion in mesh with the engine gear until self-operation ofthe engine is assured and means for unlatching the pinion responsive tothe interruption of the starting circuit.

It is a further object to provide such a device embodying the use of apivoted latch arm to oppose demeshing of the pinion from the engineresponsive to the deenergization of the starting circuit for swingingthe arm out of latching position.

It is a further object to provide such a device embodying the use of apivoted latch arm to oppose demeshing of the pinion from the engine gearduring cranking of the engine and means responsive to self-operation ofthe engine for swinging the arm out of latching position.

It is a further object to provide such a device including a, latch armfor holding the pinion in mesh with an engine gear, and yielding meansfor urging the arm into latching position, said means being operative tooppose and progressively 40 retard the demeshing movement of the pinionuntil idle position is reached so as to prevent rebounding of thepinion.

It is a further object to provide such a device having unitary means formaintaining the pinion 45 in engagement with the engine gear during thestarting operation and preventing the pinion from moving from disengagedposition while the starter is idle.

It is a further object to provide such a device incorporating amovablelatch arm and a cooperating intercepter therefor adapted to beprojected into the path of rotation of the arm to control demesh of thedrive pinion; and to further provide yielding elements on either or bothof said members for cushioning the impact thereof as demeshing of thepinion occurs.

It is a further object to provide such a device including a clutch forrotating the pinion in association with latching means for maintainingthe pinion in mesh with the engine gear during cranking, the clutchhaving novel structure for advantageous assembly and securing of itsparts.

Further objects and advantages will be apparent to those skilled in theart from the following description taken in connection with theaccompanying drawing, in which:

Fig. 1 is a diagrammatic representation of a starting system forming apreferred embodiment f the invention, the starting drive being shown inside elevation partly in section;

Fig. 2 is a view of the starter drive similar to Fig. 1 showing theparts in cranking position;

Fig. 3 is a representation in perspective of certain parts of thestarting drive showing the novel locking mechanism-used in assemblingand se- V curing the clutch;

Fig. 4 is a cross section of the starting drive on the line 4-4 of Fig.1; and

26 Fig. 5 is a detail in perspective of the casing gear during crankingof the engine and means ring for the pinion clutch showing the lugs bywhich the casing is held in assembled position. In Fig. 1 of thedrawing, there is illustrated a power shaft Iwhich may be the extendedarma- 30 ture shaft of an electric motor 2, and is provided with asmooth extended portion 3 of reduced diameter providing a shoulder 4,against which thrust washers 5 are seated. A drive member in the form ofa pinion 6 is journalled on the reduced extension 3 of shaft I inposition to be traversed into and out oi meshing engagement with anengine member such as a ily-wheel gear 1.

Means actuated by the motor 2 for moving the pinion 6 are providedincluding an operating member in the form of a screw shaft 8, providedwith threads 9 and an enlarged head portion II, fixed to the free end ofthe power shaft I in any suitable manner such as by an anchor pin I2.The pinion moving means also includes a control member in the form of. anut I3 threaded on the screw shaft and provided with an annular flangeI4 and a smooth cylindrical extension I5 of reduced diameter.

Connecting means are provided between the nut I3 and pinion 6 comprisinga barrel I6, having an inturned flange Il on its outer end for enclosingange I4 of the nut, and having an overrunning. clutch connection withthe pinion I. As here shown, this clutch comprises a driving clutchplate i8 fixed in the free end of the barrel by suitable means such aslugs i9 fitting within slots 2| in the barrel.l A complementary clutchplate 22 is fixed to the pinion 3 by any suitable means such as Weldingor brazing and is preferably provided with teeth 23, adapted to engagewith teeth 24 of the driving clutch plate. Means for normally separatingthe clutch plates i8 and 22 are provided in `the form of a disc spring25 bearing on `brie side against the pinion 3 and on the other sideagainst the clutch plate i8. The connecting means between the controlnut H3 and pinion 3 further includes a sleeve 26 of elastic materialsuch as rubber, seated on the cylindrical portion i of the control nut`and bearing frlctionally at its ends against the flange i4 and drivingclutch plate i8, so as to form a frictional driving connectiontherebetween.

Unitary means are provided for limiting the separation of the clutchplates i8 and 22, and locking the clutch plate i 8 in position withinthe end of the barrel i6. As here shown. this means is in the form of aclutch housing ring or casing 2l, having an inturned flange 28 and aninserted ring 28' adjacent the pinion forming an interior shoulderagainst which the clutch plate 22 rests. As best shown in Fig. 5, thecasing 21 is also provided at its end adjacent the barrel with lugs 29of a width slightly less than that of the slots 2| in the barrel,permitting the lugs to enter freely therein. An interior circumferentialrecess or groove 3l is formed in the end ci the barrel i6, adapted toreceive the lugs 29 of the clutch casing and thereby form a connectiontherewith in the nature of a bayonet joint. ln order to lock the lugs'29in the barrel, a thimble 32 is provided having a telescopic fit with thecylindrical extension i5 of the control nut for enclosing the rubbersleeve 26, and having tongues 33 extending radially through the slots 2iof the barrel. The tongues are bent over the lugs i9 of the clutch platei8 to hold the clutch plate in the barrel, and the ends of -the tonguesare arranged to register with the groove 3l so as to lock the lugs 29therein.

According to the present invention, means are provided for maintainingthe pinion S in mesh with the engine gear l during the crankingoperation in the form ofa latch arm 34 pivoted on a radial pin 35solidly fixed as by brazing in the head portion ll of the screw shaft 8.The latch is retained on the pin by any suitable means such as a snapring 35. As best illustrated in Fig. 4, the latch is provided with ahollow recess 3l on its underside in which is housed a spring 33 forbiasing the arm 34 toward parallel relation with the axis of the motorshaft I.

Means for releasing the latch responsive to the deenergization of thestarting circuit are provided, comprising a trip member or intercepter39. This member is preferably arranged as an extension or lattachment toa solenoid plunger 40 forming part of a magnetic starting switch 4|.Trip 39 is located adjacent the path of rotation of the free end of thelatch 34 when the latch is swung into substantial alignment with thescrew shaft as defined by a stop shoulder 42 formed by the terminationof a fiat surface 43 on the head H. The shoulder 42 is preferablyarranged to stop the latch before it comes into exact parallelism withthe axis of the motor shaft. As shown in Fig. 2, this holds the latchout of a dead center" relation to the nut i3, whereby the endwisepressure of the nut on the latch produces a component tending to rotatethe latch away from the shoulder 32. This position of the latch alsocauses the centrifugal force acting on the lat-ch to have a smallcomponent tending to rotate the latch f-urther out of parallelism withthe shaft, since such rotation causes the center of gravity of the latchto move farther from the axis of the drive.

It is generally considered desirable to have a starter driveautomatically disconnect itself when the engine is reliablyself-operative even though the operator may neglect to open the startingcircuit. In the present structure this may be accomplished by a properlocation of the shoulder 42 whereby the rotary component of the pressureof nut i3 on the latch and/or the rotary component of centrifugal forcemay cause the latch to release when theengine and starting motor haveattained such a speed that self-operation of the engine is assured. Whenthe expression "substantial parallelism with the shaft and similarexpressions are used in the specification and claims, therefore, it isintended to refer not only to a possible condition of exact parallelismbut also to include the condition in which the latch is maintained outof exact parallelism sufhciently to obtain the automatic demeshingoperation above described.

The starting switch di is arranged to control a starting circuit forenergizing the motor 2. As here shown, this circuit comprises a battery44, grounded at 45 and connected by a lead 46 to Ithe starting switch. Alead lll connects the switch to the starting motor which is grounded at48 to complete the circuit. Means under the control of the operator foractuating the switch plunger di] are provided comprising a coil 49, oneend of which is connected to the battery lead d6 by a lead 5l and manualswitch 52, the other end being grounded at 53 to complete the controlcircuit. The plunger is normally held in position to open the switch 4iby suitable means such as a spring 59. The free end of latch 34 isprovided with a radial projection or head 54 which is arranged to strikethe trip 39 when the drive is rotating with the starting switch open,thereby swinging the latch away from the stop 42 and releasing thepinion. The impact of the projection against the trip is preferablycushioned by incorporating yielding or flexible means in either or bothelements. Thus, the trip 39 may be connected to the plunger 40 by meansof a coiled spring 55 suitably attached at its ends to said elements.Likewise, the projection 54 may be constructed as shown in Fig. 4 in theform of a spring member, the free end of which is attached to the latchby a rivet 56 in order to prevent expansion of the spring by centrifugalforce.

The latch arm 34 is arranged tov perform the further function of ananti-drift mechanism for normally maintaining the pinion member in itsidle position. For this purpose a groove 5l is formed in the rearlateral face of the control nut i3 in position to receive the free endof the latch arm and form a seat therefor in which it is yieldably heldby the pressure of spring 38.

In assembling the starting drive, the pinion with the driven clutchplate 22 thereon and the clutch housing ring 27 is slid over the powershaft I followed by the disc spring 25, driving clutch plate I 9 andthimble 32. The latch subassembly is slid over the pin 35, first beingsure that the outturned ends of the spring 38 are in place and retainedby the snap ring 36. Then another sub-assembly is prepared by placingthe control nut I3 inside of the barrel I6 until it strikes ange I'I andplacing the rubber block 26 inside the barrel against the iiange I4 ofthe nut I3. Next, the pinion, clutch and thimble unit is assembled tothe barrel. Said unit is then anchored to the barrel IB by rotating theclutch casing 21 about 45 degrees so as to cause the lugs 29 thereof toenter the interior recess 3i of barrel i6 as best shown in Fig. 3. Inorder to prevent the casing 2'I from becoming disengaged, the malleabletongues 33 of the thimble are then bent around the lugs I9 of plate I8so that they enter the slots 2l and retain the lugs 29 in the groove3I.- After all the tongues 33 have been bent over, this group of partsconstitutes a subassembly bounded on one side by the pinion 3 and on theother by the control nut I3. The screw shaft 8 is then slid on the powershaft I. threaded into the nut I3, and anchored en the power shaft byinserting the anchor1 pin ifi and locking it by a cotter key B. l

In operation, starting with the parts in the positions shown in Fig. l,the manual switch 52 is closed by the operator to complete the controlcircuit and energize the coil 49 so as to close thestarting switch 4Iand simultaneously withdraw the trip 39 to clear the latch head bil.Upon closure of switch 4l, the motor shaft i rapidly acceleratescarrying with it the screw shaft 3 and the latch 34 mounted thereon. Dueto inertia. the control nut I3 and its associated parts do not rotate,thus enabling the latch to move out o the anti-drift groove 5l and thecontrol nut is traversed by threads 9 to the right in Fig. l., carryingwith it the barrel and pinion assembly. The traversal of the pinion isarrested by engagement with the thrust washers 5 at the moment of fullmesh with the engine gear l. Further traversal of the nut I3 thenclosesthe clutch I8, 22 and compresses the rubber block 23 to complete thedriving connection from the power shaft to the engine gear. While thecontrol nut I3 is traversing along the screw shaft 8, the spring 38swings the latch arm 34 into substantial axial alignment with the screwshaft against the stop shoulder 42, as shown in Fig. 2. When the enginestarts, the pinion is accelerated by the engine gear faster than thestarting motor, causing the control nut I3 to back away from the pinionand permitting the clutch dentals 23 and 24 to separate under the urgingof spring 25. The latch arm 34 is spaced behind the control nut I3 farenough to allow the dentals to separate and permit the pinion to overrunfreely, but further backward movement of the control nut is prevented,so that the pinion is held in mesh with the engine gear. 'If the enginedoes not continue self-operative, the cranking operation is thereforeresumed as soon as the starting motor catches up with the speed of theengine gear.

When the engine becomes reliably self-operative, the operator opens themanual switch 52 thus opening the starting switch 4I and allowing thespring to move the trip 39 into the path of rotation of the projection54 on latch 34. The latch is thus moved away from its locking position,permitting the pinion to demesh and the parts to return to idleposition.

When the intercepting trip 33 moves into the path of the rapidlyrotating latch 34, the severe blow struck is absorbed by the exible head54 and/or the flexible element 55 of the trip plunger. The demeshingshock occurring when the control nut is thrown back to idle position iscontrolled by the spring 38 which resists the pivotal moveto retractedposition the resistance of the spring 38 progressively increases, thusretarding rotation of the control nut. When idle position of the controlnut I3 is reached, the groove 51 on the rear face of the nut receivesthe end of the latch, thus opposing relative rotation between the screwshaft 8 and nut member I3. and constituting an anti-drift means for thepinion.

If, when the engine becomes self-operative, the operator fails to openthe starting circuit, the starting motor will accelerate up to its freespinning speed. If the drive has been so designed that the shoulder 42holds the latch at a suitable small angle to the plane passing throughthe axis of the shaft and the pivot of the latch as above described. theeiiect of centrifugal force. and/or the pressure of the nut I3 on thelatch due to the dragging effect oi the overrunning clutch member 22 asrotated at high speed by the engine will release the latch and allow thepinion to demesh from the engine gear. It has been found in practicethat this angle'is not at all critical, but angles between 5 and 10 haveproved satisfactory for the purpose.

It will be understood that the effects due to the angular relation ofthe latch are present even when they are not suiicient in themselves torelease the latch.' They will therefore assist the action of the trip 39to any desired extent, and by their concurrent action improve theoperation of the device.

It will be seen that there is here provided a starting drive havingnovel features for securing the assembly of certain of its parts .andhaving latching mechanism for maintaining the pinion in crankingengagement during the starting operation which is of simple design andreadily accessible ior servicing and adjustment.

Although but one embodiment of the invention has been shown. anddescribed in detail, it will be understood that other embodiments arepossible and changes can be made in the arrangement and proportions ofthe parts without departing from the spirit of the invention as deiinedin the appended claims,

What is claimed is:

1. In an engine starter, a starting circuit including a motor and astarting switch, a starting drive operated by the motor having a drivingmember and means including an operating member and a control memberactuated by the motor to move the driving member into and out ofengagement with an engine member, a clutch between the control memberand the driving member, means including 4a latch mounted on saidoperating member cooperating with said control member for maintainingthe driving member in engaged position, a trip member, and meansresponsive to opening of the starting switch for moving the trip memberinto position to intercept and release the latch.

2. In an engine starter, a starting circuit including a motor and astarting switch, a starting drive operated by the motor having a drivingmember and means including an operating member and a control memberactuated by the motor to move the driving member into and out ofengagement with an engine member, an overrunning clutch between thecontrol member and the driving member, means including a latch pivotedon said operating member for rotation around an axis radial thereto, andadapted to oppose disengagement of the driving member, a

ananas trip member, and means responsive to opening of the startingswitch for moving the trip mem-- ber into position to intercept andrelease the latch.

3. In an engine starter, a starting circuit including a motor, astarting drive operated thereby having a pinion and means including ascrew shaft and control nut actuated by the motor to move the pinioninto and out of mesh with an engine gear to crank the engine, a clutchbetween the control nut and pinion, a latch arm pivoted on the screwshaft for rotation around an axis radial thereto and adapted to opposedemeshing of the pinion when swung into substantial parallelism withsaid shaft, a trip member, and means responsive to deenergization of thestarting circuit for moving the trip member into position to interceptand release the latch arm.

4. In an engine starter, a starting circuit including a motor, astarting drive operated thereby having a pinion and means including ascrew shaft and control nut actuated by the motor to move the pinioninto and out of mesh with an engine gear to crank the engine, connectingmeans between said control nut and pinion including a clutch and ayielding member, said clutch being closed by the final meshing movementof the pinion, a radial pin in the screw shaft, a latch arm pivoted onthe pin, arranged to extend toward the control nut during cranking ofthe engine and prevent premature demeshing of the pinion, said armresisting backward rotation of the control nut on the screw shaft todecrease the demeshing shock of the pinion as it reaches/idle position,and a trip member movable into the path of rotation of the latch when inextended position to release the latch concurrently with thedeenergization of the starting motor.

5. In an engine starter, a starting circuit including a motor and astarting switch therefor, a starting drive operated by the motor havinga pinion for traversal into cranking engagement with a gear on theengine to be started, and means including a screw shaft and a controlnut threaded thereon for actuating said pinion, a radially pivoted latcharm mounted on the screw shaft to extend toward said control nut duringcranking of the engine to prevent premature demeshing of said pinion,said control nut being formed to provide a seat adapted to receive theend of the latch when in idle position and thereby prevent drifting ofsaid pinion out of idle position, and means dependent on the opening ofthe starting switch for returning the latch arm to idle position.

6. In an engine starter, a starting circuit including a motor and astarting switch therefor,

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a starting drive operated by the motor. having a pinion for traversalinto cranking engagement with a gear on the engine to be started; meansfor actuating the pinion including a screw shaft,

1 a control nut threaded thereon, a thimble beara starting driveoperated by the motor having a pinion for traversal into crankingengagement with a gear on the engine to be started, and means includinga screw shaft and a ,control nut threaded thereon for actuating saidpinion, a latch arm mounted on the screw shaft for pivotal movement in apiane parallel to the axis of the screw shaft and biased into extendedposition to prevent premature demeshing of the pinion during cranking ofthe engine and an intercepter member actuated by the opening of thestarting switch for engaging said arm to unlatch the pinion.

8. In an engine starter, a starting circuit including a motor, astarting drive operated thereby having a pinion and means including ascrew shaft actuated by the .moton a control nut threaded thereon and anoverrunning clutch operative to traverse said pinion into and out ofmesh with an engine gear and rtate the pinion to crank the engine. saidscrew shaft having a drive head providing a fiat surface terminating inan erect shoulder. alatch arm movable on said surface into latchingposition as defined .by said shoulder to hold the pinion in meshedposition during the starting operation, a yielding head on the latcharm, and means responsive to deenergization of the starting circuit :forcontacting said yielding head to move the arm away from latchingposition.

il. In an engine starter, a starting circuit including a motor and astarting switch therefor, a starter drive operated by said motor havinga pinion adapted to move into and out of engagement and rotate a gear onthe engine to be started and means for actuating said pinion including ascrew shaft; a pin mounted radially on said screw shaft, means includinga latch pivoted on said pin for maintaining the pinion in mesh with theengine gear during cranking, and a trip member actuated by said startingswitch, said trip having a iiexible tip thereon adapted to engage thelatch to release the pinion.

10. in an engine starter, a power shaft, a pinion iournalled thereon forlongitudinal movement into and out of mesh with an engine gear, meansfor traversing and rotating the pinion from the power shaft, means forholding the pinion in mesh with the engine gear, electromagnetic meansfor releasing the holding means, manually controlled means for actuatingthe electromagnetic means and means for releasing the holding meansirrespective of the manual means and adapted to operate concurrently toassist the manual means.

11. In an engine starter, a power shaft, a pinion journalled thereon forlongitudinal movement into and out of mesh with an engine gear, meansfor traversing and rotating the pinion from the power shaft, meansincluding a pivoted arm for holding the pinion in mesh with the enginegear,

.means for stopping the pivotal movement of the arm at a small angle tothe axis of the shaft, and electromagnetically actuated means forengaging and swinging the arm away from said stopping means, andmanually controlled means for actuating the electromagnetic means.

12. In an engine starter, a power shaft, a pinion movable longitudinallythereon into and out of mesh with an engine gear, means actuated by theshaft for moving the pinion into mesh with the engine gear, and thenrotating the pinion, means on the power shaft for holding the pinion inmesh with the engine gear, said means being movable by centrifugal forceto release the pinion at a predetermined rotational speed, and means re-9 sponslve to deenersimtion of the starter for moving the holding meansto release the pinion.

file of this patent:

UNITED STATES PATENTS 'DONALD L m, Number Name Date 2,218,972 KearneyOct. 22, 1940 REFERENCES CITED 5 2,287,669 Buxton June 23, 19422,332,986 Buxton Oct, 26, 1943 The following references are of record 1nthe 2,339,486 Kearney Jan. 18' 1944

